The widespread use or projected use of methadone, acetylmethadol, and naltrexone for the treatment of opiate dependence dictates that the potential mutagenic activity of these compounds be determined. The determination of mutagenic activity becomes especially important with the realization that a high percentage of heroin addicts are of child-bearing age. To determine potential mutagenic activity we will employ an integrated testing protocol using available methods as well as newly developed procedures in bacteria, Drosophila and mice. Additionally, and of special importance, several of these procedures will be employed to test blood and urine from human subjects treated with two of these drugs, methadone and naltrexone, for mutagenic activity.